The efficiency of photovoltaic cells and panels, above all the ones made from silicon, depends on the temperature; specifically, with growing temperature of a photovoltaic cell its efficiency decreases. The decrease in efficiency is between 0.2% up to 0.48% per 1° C. In case of overall low efficiency of solar radiation to electric energy conversion (15-18%), the influence of temperature on the efficiency achieved is substantial. Designs of photovoltaic panel cooling are known e.g. according to DE 102006060786, which describes a usage of a heat exchanger within the unit of a photovoltaic panel. Similarly, the solution according to DE 10207852 also describes a photovoltaic panel cooling using a cooling medium and external heat exchangers. These solutions, similar to the ones mentioned in the files DE 19604356, DE 102009027258, DE 202006016108, WO 2009/111017, WO 2009/124575, CN 201074372, WO 2010/000240, EP 2093808, GB2452754 use a portable hydronic medium to conduct away heat from a photovoltaic panel; in order to operate, this kind of cooling system is supplied with outside energy. The solution according KR 20090071895, WO2011009993 uses squirting or trickling water to cool the surface of photovoltaic panels and at the same time cleans the surface of the cells. This solution is not practical due to high water consumption.
A number of inventions use heat that is conducted away from a photovoltaic panel as a special-purpose source of heat. However, this kind of configuration lays down contradictory requirements on the cell temperature. In order to obtain heat effectively it is suitable to increase the cell temperature and for the purpose of obtaining electric energy effectively it is suitable to decrease the cell and panel temperature. In case of separately standing power plants, the heat obtained from photovoltaic panels is basically unexploitable since there is no place to which the heat can be conducted to and since the sufficient amount of heat is available mainly outside the winter season.
The published solution according to SK UV 5973 uses a sorption cooling machine, which is driven by heat from a heat solar panel that is independent from a photovoltaic panel. This kind of solution brings in required effects; however, it also consists of a number of components that might require check-ups and maintenance, which along with a more complicated employment decreases economic effect.
There is a need for a solution that is simple, operable on a long term basis and that would assure heat is conducted away from a photovoltaic cell and panel unit without having any requirements on outside energy source. The new solution should be easily employed and should be maintenance free. The solution should also be applicable to the existing photovoltaic power plants.